The present invention relates to a toner cartridge and developing device.
Conventionally, revolver type developing devices like those described in references to be described later have been known.
In such developing devices, a plurality of cartridges are stored in the revolver. The developing devices for the respective colors rotate together with the toner cartridges.
When toner in a toner cartridge of a revolver type developing device is consumed, and the toner cartridge is to be replaced with a new toner cartridge, the rotation of the developing device is stopped. Thereafter, the interior of the device is opened to expose all the toner cartridges to the user. The user then selects a necessary one of the toner cartridges of the respective colors and replaces it with a new one.
In this case, it is required to allow the user to know the location of each cartridge at a glance, and to provide high operability in toner cartridge replacement.
Obviously, a toner cartridge is required to have an arrangement for preventing toner from spilling out when the user removes the cartridge for replacement and inserts a new toner cartridge.
As toner cartridges designed to meet such a requirement, toner cartridges like those disclosed in Japanese Patent Laid-Open Nos. 6-258911 and 8-146744 and Japanese Utility Model Laid-Open No. 3-24663 are known. In order to identify the color of toner in each of these toner cartridges, labels for displaying colors are attached to the cartridges or their caps are colored.
Alternatively, a cartridge body (to be referred to as a casing hereinafter) has a window formed from a transparent member.
Therefore, in addition to a casing and cap which are indispensable components, a member for a label or window is newly required to form a toner cartridge. Alternatively, caps of different colors are required for different kinds of toner, resulting in an increase in cost.
In addition, when a window is provided for a cartridge, the remaining amount of toner in the cartridge becomes difficult to see as it decreases depending on the position of the window or the like. This makes it difficult to identify the color of toner.
A toner cartridge is known, which has a shutter or the like covering the replenishment port to prevent toner from spilling out when the toner cartridge is replaced. When this toner cartridge is loaded in the apparatus, a portion of the apparatus moves the shutter of the toner cartridge to open the replenishment port.
More specifically, when the toner cartridge is inserted in a developing device in the apparatus, the shutter which has closed the toner replenishment port of the toner cartridge is pushed and opened by an end portion of the developing device, located near the shutter, owing to the accompanying sliding operation, and an end portion of the toner replenishment port of the toner cartridge opens the shutter which has closed the toner replenishment port of the developing device. In contrast to this, when a toner cartridge is to be removed from a developing device, the shutter which has been pushed and opened at the toner replenishment port of the toner cartridge is released by the accompanying sliding operation to be closed by a spring, and a pawl provided on the toner cartridge hooks and closes an end portion of the toner replenishment port of the developing device which is located near the shutter. Thereafter, the pawl comes off the end portion of the shutter to be released, and the toner cartridge is removed from the developing device.
Such a conventional toner cartridge is disclosed in, for example, Japanese Utility Model Laid-Open No. 03-69162.
As shown in FIG. 15A, a draft is provided on each of the outer surface of a conventional toner cartridge 201 and the inner wall of a developing device 200 throughout the entire region from near the front end on the right side in FIG. 15A (on the front surface side of the image forming apparatus) to near the rear end on the left side in FIG. 15A in consideration of the shape of a mold for injection molding in order to ensure easy mold release in the mold moving direction (longitudinal direction).
With such tapered outer shapes, when the toner cartridge 201 is inserted into the developing device 200 in the direction indicated by the arrow in FIG. 15A, no large amount of backlash occurs. Such tapered shapes therefore give no trouble in opening the shutter of the toner replenishment port of the toner cartridge 201 or opening the shutter of the toner replenishment port of the developing device 200. Let Y1 be the gap between the toner cartridge 201 and the developing device 200 when the cartridge is stored in the developing unit.
When, however, the toner cartridge 201 inserted in the developing device 200 is removed in the direction indicated by the arrow in FIG. 15B, a gap Y2 larger than the gap Y1 is produced between the inner wall of the developing device 200 and the outer surface of the toner cartridge 201, resulting in a large amount of backlash. Even in such a case, since the shutter of the toner replenishment port of the toner cartridge 201 is biased by the spring in the closing direction, the shutter can be reliably closed. However, the shutter of the toner replenishment port of the developing device 200 cannot be closed because the pawl of the toner cartridge 201 comes off the end portion near the shutter of the toner replenishment port of the developing device 200. As a consequence, toner may leak from the developing device and contaminate the interior of the image forming apparatus.
The present invention has been made in consideration of the above situation, and has as it object to provide a toner cartridge and developing device which allow easy identification of the color and remaining amount of toner in a toner cartridge of each color, provide good operability in toner cartridge replacement, and prevent toner from spilling out at the time of replacement.